1. Field of the Invention
The present invention relates to a contactless charging device, and in particular relates to a contactless charging device for simultaneously charging a plurality of loads and method thereof.
2. Description of the Related Art
A contactless charging technique is generally used to charge a portable load. Its principle is to employ a transformer having a primary winding and secondary winding that are separated as a coupling interface. When a transformer primary winding and a transformer secondary winding are in close proximity with each other (namely a charging device and a portable load are in close proximity with each other), then the power is delivered from the primary winding to the secondary winding. FIG. 1 is a schematic diagram illustrating a conventional contactless charging device 100 and a portable charged load S100. The power supply of the charging device can be a single-phase AC power supply or a three-phase AC power supply 110. The AC supply 110 is input to the rectifier and voltage regulator and then converted to a high frequency AC signal through a converter 120. After that, the transformer primary winding 130 couples the high frequency signal to the secondary winding S130 of the transformer connected to the portable charged load S100 which is external to the charging device 100. Finally, the signal at the transformer's secondary winding is converted through another rectifier and voltage regulator to charge a battery S110 inside the portable charged load S100.
For a contact charging device or a contactless charging device, before a portable load such as an electrical automobile or a robot runs out of their power, they will return to a charging station or a location provided with power supply to be charged. If a portable load stops working due to the working environment or accidental breaking down of the power supply, the load will be immobile without the power. In this case, the load can only to be towed away to a charging station. Moreover, the characteristic of a conventional contactless charging device is to charge only one load at one time, as the prior art shows in FIG. 1. If a charging device has the ability to charge a plurality of loads, the efficiency would be enormously improved.
To solve abovementioned problem and promote charging efficiency, it is necessary to provide a contactless charging device having advantages of portability and simultaneously charging a plurality of loads.